<span>The brain stem is closest to the spinal cord.</span>
Answer:
Single-cell organisms
Explanation:
In 1735, Linnaeus introduced a classification system with only two kingdoms: animals and plants. Linnaeus published this system for naming, ranking, and classifying organisms in the book "Systema Naturae". In the epoch that Linnaeus created this system, single-cell organisms such as bacteria and protists were almost unknown. In 1866, E. Haeckel added a category including both bacteria and protozoa, thereby adding a category formed by single-cell organisms (different from animals and plants). During the 1900-1920 period, bacteria were classified as a separated kingdom named 'prokaryotes'. The current three-domain classification system was introduced by C. Woese in 1990. In this system, all forms of life are divided into three different domains: archaea, bacteria, and eukaryote domains (this last composed of protists, fungi, plants and animals).
The second law of thermodynamics states that not all of the energy is used because some of the energy is lost in the form of heat. The lost heat energy is an unusable form of energy, and it causes an increase in the entropy of the universe. Thus, no energy transfer process is efficient due to the loss of energy.
